Effects of β-endorphin and its fragments on inhibitory avoidance behavior in rats

Gàbor L. Kovàcs, Béla Bohus, David De Wied

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The effects on retrieval of a one-trial learning inhibitory avoidance response of β-endorphin, α-endorphin, and γ-endorphin, given prior to test have been studied in rats. β-Endorphin (β-LPH61-91) in a relatively low dose (1.5 μg sc. or 50 ng icv.) facilitated inhibitory avoidance behavior, while a higher dose (10 μg sc. or 100 ng icv.) caused bimodal changes (facilitation in 50% of the animals and attenuation in another 40%. Peripheral injection of γ-endorphin attenuated inhibitory avoidance behaviour in a dose-dependent manner. The C-terminus of β-endorphin (β-LPH78-91) was ineffective. α-Endorphin facilitated inhibitory avoidance behavior in a dose-dependent manner. Naltrexone pretreatment antagonized the bimodal effect of β-endorphin: following pretreatment with the opiate antagonist the low latency component disappeared, but the facilitatory effect of the neuropeptide remained the same. It is suggested that β-endorphin carries more than one bit of behavioral information. Inherent activities either related or unrelated to naltrexone-sensitive opiate receptors as well as biotransformation into α- and γ-endorphin may contribute to the multiple behavioral effects of this neuropeptide.

Original languageEnglish
Pages (from-to)411-419
Number of pages9
Issue number4
Publication statusPublished - 1983



  • inhibitory avoidance behavior
  • α-endorphin
  • β-Endorphin
  • γ-endorphin

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Endocrine and Autonomic Systems
  • Psychiatry and Mental health
  • Biological Psychiatry

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